The present invention relates to copying apparatus in general, and more particularly to the type of copying apparatus wherein an original to be copied is scanned and an image-forming light beam is then transmitted with the scanned information to an image-receiving surface. Xerographic copiers are exemplary of one type of such copying apparatus.
In apparatus of this kind it is often necessary to vary the amount of light which reaches the sensitized surface on which the image of the scanned original is to be formed. This is necessary for a variety of reasons, including the fact that different originals have different light-reflecting characteristics, dependent on which the copy being produced may become too light or too dark. It has been proposed to provide a baffle which is mounted adjacent the path of the light beam that travels from the original to the photosensitive surface, and to pivot this baffle into the path of the light beam to a greater or lesser extent, depending upon the correction that is to be made to compensate for the different reflection characteristics of the original, or for other reasons. However, this is not a satisfactory arrangement because the baffle enters the path of the light beam from one side and therefore influences the light beam asymmetrically. This disadvantageously influences the copy to be made, as will be evident to those conversant with this field.